How to create realistic blinking/shining stars in BGE?
One of my favourite tricks is to use what I call noise layers. So let's find/make a starry image.
Now we simply have to make it flicker! I happen to know that if you get another bit of noise and move it across behind a star-field, so long as the stars are sparse enough, you can't tell. So with a UV scroll script and two UV layers, you can get a reasonable effect

So here you go, here's a blend:
http://www.pasteall.org/blend/40447